// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

#include <memory>
#include <thread>
#include "opentelemetry/exporters/prometheus/exporter.h"
#include "opentelemetry/metrics/provider.h"
#include "opentelemetry/sdk/metrics/aggregation/default_aggregation.h"
#include "opentelemetry/sdk/metrics/aggregation/histogram_aggregation.h"
#include "opentelemetry/sdk/metrics/export/periodic_exporting_metric_reader.h"
#include "opentelemetry/sdk/metrics/meter.h"
#include "opentelemetry/sdk/metrics/meter_provider.h"

#ifdef BAZEL_BUILD
#  include "examples/common/metrics_foo_library/foo_library.h"
#else
#  include "metrics_foo_library/foo_library.h"
#endif

namespace metrics_sdk      = opentelemetry::sdk::metrics;
namespace nostd            = opentelemetry::nostd;
namespace common           = opentelemetry::common;
namespace metrics_exporter = opentelemetry::exporter::metrics;
namespace metrics_api      = opentelemetry::metrics;

namespace
{

void initMetrics(const std::string &name, const std::string &addr)
{
  metrics_exporter::PrometheusExporterOptions opts;
  if (!addr.empty())
  {
    opts.url = addr;
  }
  std::puts("PrometheusExporter example program running ...");

  std::unique_ptr<metrics_sdk::PushMetricExporter> exporter{
      new metrics_exporter::PrometheusExporter(opts)};

  std::string version{"1.2.0"};
  std::string schema{"https://opentelemetry.io/schemas/1.2.0"};

  // Initialize and set the global MeterProvider
  metrics_sdk::PeriodicExportingMetricReaderOptions options;
  options.export_interval_millis = std::chrono::milliseconds(1000);
  options.export_timeout_millis  = std::chrono::milliseconds(500);
  std::unique_ptr<metrics_sdk::MetricReader> reader{
      new metrics_sdk::PeriodicExportingMetricReader(std::move(exporter), options)};
  auto provider = std::shared_ptr<metrics_api::MeterProvider>(new metrics_sdk::MeterProvider());
  auto p        = std::static_pointer_cast<metrics_sdk::MeterProvider>(provider);
  p->AddMetricReader(std::move(reader));

  // counter view
  std::string counter_name = name + "_counter";
  std::unique_ptr<metrics_sdk::InstrumentSelector> instrument_selector{
      new metrics_sdk::InstrumentSelector(metrics_sdk::InstrumentType::kCounter, counter_name)};
  std::unique_ptr<metrics_sdk::MeterSelector> meter_selector{
      new metrics_sdk::MeterSelector(name, version, schema)};
  std::unique_ptr<metrics_sdk::View> sum_view{
      new metrics_sdk::View{name, "description", metrics_sdk::AggregationType::kSum}};
  p->AddView(std::move(instrument_selector), std::move(meter_selector), std::move(sum_view));

  // histogram view
  std::string histogram_name = name + "_histogram";
  std::unique_ptr<metrics_sdk::InstrumentSelector> histogram_instrument_selector{
      new metrics_sdk::InstrumentSelector(metrics_sdk::InstrumentType::kHistogram, histogram_name)};
  std::unique_ptr<metrics_sdk::MeterSelector> histogram_meter_selector{
      new metrics_sdk::MeterSelector(name, version, schema)};
  std::unique_ptr<metrics_sdk::View> histogram_view{
      new metrics_sdk::View{name, "description", metrics_sdk::AggregationType::kHistogram}};
  p->AddView(std::move(histogram_instrument_selector), std::move(histogram_meter_selector),
             std::move(histogram_view));
  metrics_api::Provider::SetMeterProvider(provider);
}
}  // namespace

int main(int argc, char **argv)
{
  std::string example_type;
  std::string addr{"localhost:8080"};
  if (argc == 1)
  {
    std::puts("usage: $prometheus_example <example type> <url>");
  }

  if (argc >= 2)
  {
    example_type = argv[1];
  }
  if (argc > 2)
  {
    addr = argv[2];
  }

  std::string name{"prometheus_metric_example"};
  initMetrics(name, addr);

  if (example_type == "counter")
  {
    foo_library::counter_example(name);
  }
  else if (example_type == "histogram")
  {
    foo_library::histogram_example(name);
  }
  else
  {
    std::thread counter_example{&foo_library::counter_example, name};
    std::thread histogram_example{&foo_library::histogram_example, name};
    counter_example.join();
    histogram_example.join();
  }
}
